Can QST inform us about sensitivity of burn scars?

QST and sensitivity of burn scars

The first week of February 2020 marks the annual National Burn Awareness Week in the US, which’s theme is “Contact Burns-Hot Surfaces Damage Skin”.

Healthy skin is vital. As the largest organ in the body, with a surface measuring up to 2 m2 in adults, the skin serves as a physical barrier to bacterial, viral and chemical agents. It provides thermal insulation and temperature regulation by virtue of hair, layers of fat, and sweat glands.

Importantly it contains within it nerve endings that allow us to sense the world around us: from gentle touch and soft hugs to scratches, bites and blows.

Unfortunately, the skin is also the main organ damaged in burns. Considering the depth of skin damage, surface area and affected body area, individuals can experience variable degrees of nerve damage which can extend past the recovery. This, in turn, can be expressed as either loss of sensation of gentle or painful stimuli, or conversely in increased sensitivity of the burnt area.

In their 2019 article “Sensory alteration patterns in burned patients”, Dr. Tirado-Esteban and colleagues investigated patterns of nerve damage in the skin of burn patients. The authors utilized quantitative sensory testing (QST) – tests designed to provide information about the relationship between stimulation and perception – to compare between the affected area and the contralateral unaffected area, using cold, heat, and mechanical stimuli. Thermal testing was conducted with a Medoc TSA.

Compared to the unaffected side, the site of the burn was less sensitive (on average) in detecting non-painful heat, cold, and touch. Curiously, pain sensitivity for cold and heat remained unaffected. The authors conclude that this might be evidence of sensory disturbance in burn patients, and QST is a useful tool to detect and monitor sensitivity in these patients.

These results warrant further investigation of how nerve fibers regenerate and how sensation is restored – from the initial injury to complete healing.